Disclosed is a method of producing a microporous polymer membrane, comprising: providing a polymer material; melting the polymer material; forming a precursor film by cooling and crystallizing the molten polymer material using an air knife; extending the precursor film; annealing the extended precursor film, primary stretching the annealed precursor film; forming a preliminary membrane by subjecting the primary stretched film to secondary stretching at a high temperature, and forming a microporous polymer membrane by heat setting the preliminary membrane. A microporous polymer membrane produced by the method is also provided.

The present invention is directed to methods of treating a hydrocarbon-containing waste stream to form a hydrocarbon-containing retentate and an aqueous permeate which is substantially free of hydrocarbon. The method includes passing the hydrocarbon-containing waste stream through a microporous membrane to yield the hydrocarbon-containing retentate and the aqueous permeate. The membrane comprises a substantially hydrophobic, polymeric matrix and substantially hydrophilic, finely divided, particulate filler distributed throughout the matrix. The polymeric matrix has pores with a volume average diameter less than 1.0 micron, and at least 50 percent of the pores have a mean diameter of less than 0.35 micron.

A method of producing microporous membranes includes stretching a multi-layer layer extrudate having first and second layers, the first layer including a first polyolefin and a first diluent, and the second layer including a second polyolefin and a second diluent, the second polyolefin including polypropylene in an amount of 1.0 wt. % to 40.0 wt. %, the polypropylene having an Mw>0.910.sup.6 and a Hm100.0 J/g; removing at least a portion of the diluents to produce a dried membrane having a first length and a first width; stretching the membrane by a first magnification factor of 1.1 to 1.5 and stretching the membrane by a second magnification factor of 1.1 to 1.3; and reducing the width.

Disclosed are hydrophilic porous PTFE membranes comprising PTFE and an amphiphilic copolymer, for example, a copolymer of the formula: ##STR00001##
wherein m and n are as described herein. Also disclosed are a method of preparing hydrophilic porous PTFE membranes and a method of filtering fluids through such membranes.

The present invention provides a porous polytetrafluoroethylene membrane having a surface coated with a liquid-repellent agent. In this porous polytetrafluoroethylene membrane, the liquid-repellent agent is a polymer obtained by polymerization of monomers consisting essentially of CH.sub.2CHCOOCH.sub.2CH.sub.2C.sub.6F.sub.13. This porous polytetrafluoroethylene membrane is suitable for use as a gas-permeable membrane that allows passage of gases but prevents entry of liquids and/or dust, specifically as a waterproof sound-transmitting membrane, a waterproof gas-permeable membrane, or a dustproof gas-permeable membrane.

It has been discovered that the function of a fuel filter monitor can be accomplished without the use of SAP. The present invention provides a fuel filter monitor comprising an ePTFE membrane, a support structure adjacent to said ePTFE membrane wherein the membrane is disposed upstream of the support and said monitor prevents penetration of water to the downstream of said fuel wet monitor, where the water can be in the form of discrete water drops in the fuel, or a bulk water stream which displaces the upstream fuel.

Provided is a black porous polytetrafluoroethylene membrane including a porous polytetrafluoroethylene membrane dyed black. A whiteness of a principal face of the black porous polytetrafluoroethylene membrane as measured according to JIS L 1015 (Hunter method) is 18.0 to 23.0%, and the whiteness of the principal face falls within a range of 18.0 and 25.0% after heating at 350 C. for 1 minute. This black porous PTFE membrane is suitable as a gas-permeable membrane that blocks entry of water and/or dust and that allows permeation of gases; specifically, the black porous PTFE membrane is suitable, for example, as a waterproof sound-transmitting membrane, a waterproof gas-permeable membrane, and a dustproof gas-permeable membrane.

In a method for manufacturing a polyolefin microporous film, non-uniformity in a film resulting from non-uniform drying during solvent extraction is minimized, high-speed drying and high-speed continuous productivity of the polyolefin microporous film are implemented. In the method for manufacturing a polyolefin microporous film, in which a composition composed of a polyolefin resin and a plasticizer is made into a film form using extrusion, the plasticizer is extracted and removed using a solvent, and the film is thereafter dried. After the foregoing extraction and before the drying, the film is brought into close contact with a roll, or its width is mechanically restrained. A liquid (heating medium) having a temperature greater than or equal to the boiling point of the solvent is made to contact the film while the film is in close contact with the roll or while the width is restrained, whereby the film is heated and dried.

A polyolefin microporous membrane is disclosed. The membrane includes at least one microporous membrane layer, where the microporous membrane layer has an air permeability between about 100 sec/100 cc and about 220 sec/100 cc, a pin puncture strength of at least 550 gf, and a crystallization half time t.sub.1/2 of from 10 to 35 minutes when subjected to isothermal crystallization at 117 C. The air permeability and the pin puncture strength are normalized to a thickness of 16 m.

A method for producing a microporous material comprising the steps of: providing an ultrahigh molecular weight polyethylene (UHMWPE); providing a filler; providing a processing plasticizer; adding the filler to the UHMWPE in a mixture being in the range of from about 1:9 to about 15:1 filler to UHMWPE by weight; adding the processing plasticizer to the mixture; extruding the mixture to form a sheet from the mixture; calendering the sheet; extracting the processing plasticizer from the sheet to produce a matrix comprising UHMWPE and the filler distributed throughout the matrix; stretching the microporous material in at least one direction to a stretch ratio of at least about 1.5 to produce a stretched microporous matrix; and subsequently calendering the stretched microporous matrix to produce a microporous material which exhibits improved physical and dimensional stability properties over the stretched microporous matrix.